Chemotactic responses of malignant tumor cells will be studied, in order to further characterize the nature of the complement-derived fragment of C5. Physical-chemical features of the fragment will be determined. Normal tissues will be studied for their ability to generate from C5 a tumor cell chemotactic factor. Finally, the chemotactic fragment for tumor cells will be injected into rat skin and assessed for its ability to induce localization of tumor cells from the bloodstream.